Læknablaðið - 15.01.1998, Side 45

LÆKNABLAÐIÐ 1998; 84
43
Nýr doktor í læknisfræði
Þann 2. maí 1997 lauk Haukur Hjaltason
doktorsprófi í læknisfræði frá Karolinska inst-
itutet í Stokkhólmi. Á ensku ber ritgerðin titil-
inn Visual and Tactile Neglect og fjallar um
gaumstol hjá sjúklingum með heilablóðfall í
hægra heilahveli. Gaumstol er uppástunga höf-
undar sem þýðing á orðinu neglect. Ritgerðin
fjallar um áhrif mismunandi þátta á gaumstol
eins og það kemur fram við prófun á taugasál-
fræðiprófum, einkum prófi þar sem sjúklingar
eru beðnir að helminga línu. Ágrip ritgerðar-
innar á ensku fer hér á eftir.
Neglect patients typically fail to report, re-
spond, or orient to information presented in
locations further away from the side of the
brain lesion. Neglect is most often reported
after acute stroke, and is more severe and
more frequent after right hemisphere damage.
The thesis concerns different aspects of the
neglect syndrome in stroke patients. It was
divided into three parts.
Study I examined a large sample of patients
which performed a line cancellation test where
the direction of arm movement and the dir-
ection of visual scanning were decoupled. The
results support previous findings of a differ-
entiation between perceptual and motor asp-
ects of neglect, and provide further evidence
that these components correlate with parietal
and frontal brain lesions, respectively.
In studies II-V, patients performed bisection
tasks under different experimental conditions.
It was found that performance improved in
darkness as compared with performance in
normal room illumination. The effect of dark-
ness is probably mediated by the absence of
background stimuli which direct attention rig-
htward, or capture attention on the right side.
Bisection performance also improved when it
was preceded by tactile exploration of the
Haukur starfar sem sérfræðingur í taugasjúkdómum við
Karolínska sjúkrahúsið í Stokkhólmi. Heimilisfangið þar er:
Neurologiska kliniken, Karolinska sjukhuset, S-171 76
Stockholm, Sverige.
object to be bisected. This improvement was
shown across conditions in which patients bis-
ected rods with or without the aid of vision,
while patients performed poorly when
exploration was excluded in the visual condit-
ion. The conclusion is that the difference
between visual and tactile rod bisection is not
modality-specific, but depends on the explora-
tion which is an integrated part of the tactile
task, and may thereby compensate tactile neg-
lect. Patients bisected three-dimensional
objects more accurately than two-dimensional
objects, and two-dimensional objects more
accurately than lines. It is likely that the two-
and three-dimensional conditions enable pat-
ients to apply a more global mode in their
perceptual processing, thereby increasing the
subjective display size and making bisection
more accurate. No effect of different figure-
ground contrast conditions was found. Finally,
performance was compared when patients bis-
ected lines with their right hand, and with a red
laser point from a lamp mounted centrally on